The shocking financial impact of sick leave is more than £40,000 a year for small and medium and sized businesses.

According to AXA PPP healthcare, the cost of sickness absences for larger sized SMEs is £40,500 ($65,630, €47,491) on average per year for companies with 100 to 250 employees. The cost to micro-businesses with up to 10 staff, is £3,500 a year.

The insurer's research, which was conducted by Redshift Research among 500 SMEs in September, also found that larger firms clock up more sick days per employee each year.

While micro-businesses of up to 10 staff have on average 5.2 sick days per employee per year, this increases to 6.8 days for companies with 100 to 250 employees, according to the study.

The research also highlighted trust issues between managers and employees.

"Many staff say that calling in sick makes them nervous - even when they're genuinely unwell," said Chris Jessop, managing director of Health Services at AXA PPP healthcare.

The survey found that three in five (60%) of bosses of small and medium sized businesses (SMEs) do not always believe their employees when they call in sick.

In addition, over a third of bosses (37%) admit to checking social media profiles of staff they suspect of "pulling a sickie", and one in four bosses (25%) would have no qualms about asking colleagues to call and check on employees they think are lying about being ill.

AXA PPP healthcare said it is no surprise then that nearly half of employees (46%) say they feel nervous about calling their boss - even when they are genuinely ill.

Jessop added: "The findings also show that smaller sized firms are more effective at managing sickness absence.

"This may be down to better communication and trust between bosses and employees that can come from working closely together. Larger sized businesses could learn a lot from their smaller counterparts when it comes to employer - employee relationships."